This invention relates to piston rod/crankshaft connections of the type in which a piston rod is rigidly connected to a frame-like member known as a scotch yoke having an internal elongate guideway which accommodates a crank pin. With this arrangement, linear reciprocatory movement of the piston rod and yoke is accompanied by rotation of the crankshaft and reciprocatory movement of the crank pin in the guideway transversely to the direction of movement of the rod and yoke.
Scotch yoke-type piston rod/crankshaft connections can be used both in converting piston reciprocation into crankshaft rotation, i.e. in engines or motors, or in converting crankshaft rotation into piston reciprocation, as in compressors or pumps, and such connections are useful, for example, in allowing opposed pistons to be connected to a common crank pin directly in line. Known scotch yoke connections generally employ solid or one-piece crankshafts with a circular-section crank pin and various bearing blocks, roller assemblies, and the like interposed between the crank pin and opposite bearing surfaces of the yoke guideway. These assemblies are prone to impact failure and premature wear due to the provision of multiple wear surfaces. The present invention provides an improved scotch yoke-type piston rod/crankshaft connection having improved wear resistance compared with prior structures and a reduction in the number of wear surfaces.